1. Technical Field of the Invention
The present invention relates to a musical sound synthesizing apparatus for synthesizing a musical sound signal using waveform data acquired in advance.
2. Description of the Related Art
Attempts to electronically reproduce musical sounds generated from a natural musical instrument by simulating the action of the natural musical instrument have been made.
Among natural musical instruments, in a piano, for example, sound is produced when a hammer strikes a string corresponding to a depressed key of a keyboard from among a plurality of arranged strings, and releasing the key just triggers a damper to come into contact with the string to suppress vibration of the string, thereby stopping the sound. When a certain string is vibrated, not only does the string generate a sound but neighboring strings resonate or the vibration of the string is propagated to other strings through a sound board to vibrate the other strings. This resonance or propagation of vibration is an important element of the characteristic sound of a piano.
Attempts to electronically reproduce the characteristic sound of a piano are disclosed in Patent Publications.
Patent Publication No. 2828872 describes that a resonant sound generation channel is set for a string corresponding to each pitch, and a musical sound signal of a pitch corresponding to a depressed key, which is generated by a sound source, is input to the corresponding resonant sound generation channel so as to generate a resonant sound corresponding to the pitch.
Patent Publication No. 2650509 discloses that a musical sound signal that simulates vibration of a string of a piano is input to a filter that simulates a propagation state of vibration from a bridge to a sound board in the piano, and a musical sound signal output from the filter or a musical sound signal before being filtered and the musical sound signal are output as a musical sound.
However, for simulation of the behavior of a natural musical instrument with strings, a method of generating a signal indicating a sound according to vibration of a string and creating a signal representing a sound caused by resonance or propagation of the vibration to other strings on the basis of the signal is considered to be useful to obtain an artificial sound closer to the natural sound of the musical instrument. This is because a string initially produces sound on the basis of manipulation by a performer of a natural musical instrument with strings, in general.
As to generation of a signal indicating a sound caused by vibration of a string, Patent Publication No. 2828872 describes a method of imparting a desired tone to a musical sound signal of a pitch corresponding to a depressed key using a waveform memory sound source and, simultaneously, generating a musical sound signal given an envelope according to a playing operation. Patent Publication No. 2650509 discloses a method that generates a signal indicating a sound caused by vibration of a string by applying data indicating an initial velocity of a hammer to a string model that is a physical model which simulates a vibrating state of the string according to strike of the hammer using a physical model sound source.
However, the method disclosed in Patent Publication No. 2650509 is not suitable to reproduction of musical tones of a musical instrument of a specific model although the method allows features of acquired musical tones to be controlled to a certain degree through parameter adjustment because a model for reproducing interaction between a hammer and a string is complex. When musical tones of a musical instrument of a specific model need to be reproduced with little effort, it is effective to use a waveform memory sound source that uses a waveform obtained by sampling the waveform of a musical sound actually generated by the musical instrument.
However, even when the waveform memory sound source is used, the method disclosed in Patent Publication No. 2828872, for example, needs to obtain a musical sound signal that does not include resonance of a sound board or a string as a musical sound signal of each pitch, which is stored in the sound source. This is because it is impossible to reproduce a sound solely associated to vibration of the string if the musical sound signal includes another sound caused by resonance of the sound board or string. Accordingly, a sampling operation needs to be carried out with a sound deadener arranged such that all strings other than a string producing sound and the sound board are not vibrated and requires extraordinary effort. Therefore, the conventional method cannot easily reproduce musical tones of musical instruments of various models.